The present invention relates to a new polyvinyl(dialkylthiocarbamoylthio)acetate resin, a method for producing said resin and a heavy metals-removing agent which utilizes the heavy metals-seizing property of said resin.
Recently, nuisances brought by waste water, exhaust gases, commercially discarded materials, etc. have caused public discussion. Particularly, the problem of treatment of waste water containing heavy metals such as mercury, etc. has been serious. Thus, the administrative regulation of drainage has become severer year after year. For example, in case of mercury, 5 ppb has been required as its effluent standard, and 0.5 ppb, as its environmental quality standard.
As a countermeasure to this, a compound capable of seizing mercury contained in waste water by forming a chelate bond with mercury compounds has been found. For example, Japanese patent application laid-open No. 29481/1975 discloses a mercury-removing performance of tetraalkylthiuramdisulfide. However, when this compound is employed as an agent for removing mercury, the presence of oily matters, organic substances, etc. in admixture with the waste water, brings about the drawbacks that the tetraalkylthiuramdisulfide is extracted by oily matters, and also its mercury-removing performance is only to such an extent that a mercury ion concentration of 1 ppm is reduced down to 0.011-0.0042 ppm, such values being much insufficient as compared to the above-mentioned standard values.
The present inventors have made strenuous studies for overcoming these drawbacks, and as a result have found a polyvinyl(dialkylthiocarbamoylthio)acetate resin having advantages of a mercury-removing performance which has never been known, and its insolubility in organic substances, and have succeeded in producing said resin.